.tree-node {
  margin: 0;
  padding: 0;
  font-size: 12px;
  height: 1.5em;
  line-height: 1.5em;
}

.tree-node > .title > .title-icon::before {
  content: " \25B6 ";
  color: rebeccapurple;
  display: inline-block;
}

.tree-node > .title > .tree-down::before {
  transform: rotate(90deg);
}

.tree-node > .title > .title-check::before {
  content: "☐";
  width: 1.5em;
}
.tree-node > .title > .title-checked::before {
  content: "☑";
  width: 1.5em;
}

.tree-node > .tree-node {
  margin-left: 1.5em;
  display: none;
}

.tree-node > .tree-node.tree-down {
  display: block;
}
